And which devices that support Firefox or Chrome actually have accelerometers? It doesn't work on my Froyo phone...
I know it has an accelerometer (I've seen the bundled Windows software use it), but I don't know where the API to access that data is.
I am not sure whether Firefox or Chrome/Chromium on Linux will actually read the data that is provided by hdaps.
It works - somewhat - on an iPad - but there's a problem in that tilting the iPad makes the screen rotate and locking the screen seems to disable the tilt events.
Best experience is on a MacBook with Chrome, IMHO.